Corner post with corrugated steel insert



United States Patent Charles E. Palmer,

Somers, Connecticut 737,482

June 17, 1968 Oct. 27, 1970 Jones & Laughlin Steel Corporation,Pittsburgh, Pa., a corporation of Pennsylvania Inventor Appl. No. FiledPatented Assignee CORNER POST WITH CORRUGATED STEEL INSERT 9 Claims, 3Drawing Figs.

US. Cl 229/14, l6l/220. [61/135. 229/49 Int. Cl B65d 57/00 FieldofSearch l6l/121,

123, I33- 137. (Corr. Digest). 220; 229/140,49

References Cited UNITED STATES PATENTS Hubbard I 6 1 /(CorrugateDigest)UX Grayson et a1. l6 l/(Corrugate Digest) *UX Masters et a1'229/14(C)UX Gazelle ..161/(Metal F0il)UX Blessing ..16I/(CorrugateDigest)UX Steck 161/220X Summers... l61/(Corrugate Digest)UX PrimaryExaminer-Davis T. Moorhead Attorney-T. A. Zalenski ABSTRACT: Packingsupports, such as L-shaped corner posts are provided with corrugatedsteel foil cores.

Patented Oct. 27, 1970 Fig.2.

989 Homo" F ig. 3.

R w ML N. EE W5 u R w his ATTORNEY CORNER POST WITH CORRUGATED STEELINSERT This invention relates generally to packing supports havingcorrugated steel foil cores, particularly where the supports comprisepacking corner posts.

In packing relatively heavy articles in paperboard cartons, varioustypes of packing supports, including corner posts, are used. Thesesupports typically are formed of corrugated board and in the case ofcorner posts generally have an L-shaped cross section so as to fitwithin the corners of a carton and receive the corners of the articlepacked therein. Packing supports must be able to absorb any shockimparted to the carton so as to prevent damage to the article packedtherein, and corner posts must, in addition, be able to supportoverlying cartons since the cartons are oftentimes stacked.

According to the present invention, packing supports meeting therequirements of packers are formed from two web units of packingmaterial, such as corrugated board, and a corrugated steel foil core. Ina particular application, corrugated steel foil cores are used inconjunction with corner posts provided within packing cartons to protectarticles packed therein from both transverse and longitudinal crushingforces.

Generally, the corrugated steel foil core is bonded to adjacent webunits by an adhesive, and l have found that the extent of the bondingarea significantly affects the strength of the packing support. Thus,supports formed from steel foil cores bonded to web units by an adhesiveplaced continuously along the steel foil corrugation peaks or fluteshave greater compressive strengths than similar supports where theadhesive is only spotted along the steel foil flutes. Similarly.supports constructed with steel foil cores having flattened corrugationpeaks are of greater compressive strength than supports constructed ofsteel foil cores having normal or rounded corrugation peaks. l have alsofound that a packing support with a corrugated steel foil core afterfailing initially clue to the application of a compressive forcecontinues to support for an indefinite period a load only slightly lessthan its maximum capacity.

lt is an object of this invention to provide packing supports havingcorrugated steel foil cores. Another object of the invention is toprovide such supports in the form of L-shaped corner supports. Yetanother object is to provide such supports where the cores are bonded toadjacent web units by means of an adhesive placed continuously alongeach of the steel foil corrugation peaks. Another object of theinvention is to provide such supports where the steel foil corrugationpeaks are somewhat flattened. Still another object of the invention isto provide L-shaped corner posts having a corrugated steel foil corebonded on each side to paperboard web units.

These and other objects and advantages of the invention will becomeapparent from the following description of an embodiment thereof withreference to the accompanying drawing in which:

FIG. 1 is a top perspective view of a carton having in two cornersthereof corner posts formed with corrugated steel foil cores inaccordance with the present invention.

FIG. 2 is an end view of a corner post formed in accordance with thisinvention, the thicknesses of the laminae forming the post beingsomewhat enlarged for purposes of clarity.

F IG. 3 is an enlarged end view of a corrugated steel foil core ofmodified construction wherein the peaks of the corrugations areflattened, the phantom lines indicating more rounded or normalcorrugation peaks or flutes.

Referring to the drawing in detail, FIG. 1 illustrates a cardboardcarton generally referred to by the numeral 1 and having flaps 2-2 forclosing of the carton top. Positioned in each of the corners of thecarton 1 are L-shaped packing supports or corner posts 3-3, only twobeing shown for ease of illustration. The article packed within thecarton is placed therein so that its corners are received within thechannels 4-4 of the corner posts. The posts thus provide resistance totransverse crushing forces applied to the carton. In addition, thecorner posts because they extend from the bottom to the top of thecarton 1 provide resistance to longitudinal crushing forces applied tothe carton, as when a number of the packed cartons are stacked together.

As best seen in FIG. 2, the corner posts include an outside web unit 5,an inside web unit 6 and an intermediate corrugated steel foil core 7.The steel foil employed is from .002

inch to .006 inch thick and is in most instances in a hardened state,i.e., the steel foil will not have been annealed after being rolled tofinal gauge. Web unit 5 includes a five-layered structure comprisingalternating plain and corrugated paperboard webs 8-8 and 9-9,respectively. Web unit 6 is similarly formed of alternating plain andcorrugated paperboard webs 10-10 and] 1-11, respectively. Thecorrugations or flutes of the corrugated paperboard webs 9-9 and 11-11and the steelfoil core 7 extend longitudinally of the corner posts-asthey are positioned within the packing carton.

Each of the corrugated paperboard webs and the corrugated steel foilcore element are bonded to adjacent plain webs by means of an adhesive14 placed along the peaks of the corrugations. As already noted, theposts are able to resist a greater longitudinal crushing force beforefailure if the adhesive is applied in a continuous length along each ofthe corrugation peaks rather than being spotted along said peaks. Thelatter type of posts when subjected to longitudinal compression fail byfolding of the steel foil between the points of adhesive contact.

Set out in table 1 are the results of tests carried out on posts bothwhere the steel foil core is bonded to the web units by a continuouslength of adhesive along each of its corrugation peaks and where thesteel foil core is bonded to the web units by spot adhesive contactalong each of its corrugation peaks. The posts tested were 45% incheslong and had either a .002 inch steel foil, A-flute core, a .002 inchsteel foil, B-flute core, or a .003 inch steel foil. B-flute core.A-flute material has an approximate flute height of 0.l87 inch at 36flutes per foot, and B-flute material has an approximate flute height of.097 inch at 50 or ii flutes per foot. The compressive load valuesrepresent the longitudinal crushing loads at which the posts initiallyfailed.

TABLE 1 Compressive Load, pounds Since the method of adhesiveapplication determines in part the compressive strength of the posts, agood bond between the steel foil core and the web units is required.This can be accomplished by resistance heating of the steel foil coreusing an electrical power supply after the corner post is formed. Uponheating of the steel foil, the hot melt adhesive remelts, insuring agood distribution of the adhesive between the steel foil core and theweb units.

Referring to FIG. 3, the phantom lines illustrate a corrugated steelfoil core profile with normal or rounded peaks, and the solid linesillustrate a corrugated steel foil core profile with peaks that aresomewhat flattened. It can be seen that the flattened peaks 12-12provide a greater surface area for contact to the web units than thenormal or rounded peaks 13-13. The use of a core having flattened peaksresults in posts of improved compressive strengths.

To compare the relative strengths of posts having cores with flattenedpeaks and rounded peaks, five corner posts 46% inches long with .006inch steel foil cores were constructed. Three of the posts had steelfoil cores with rounded or normal corrugation profiles, while two of theposts had flattened peaks of the type shown in FIG. 3. The compressionload each of the posts was able to support before initial failure is setout In table II Posts I, 2 and 3 had a normal profile steel foil core,and posts 4 and 5 had a flattened profile steel core.

TABLE II Compression Post Number load (pounds) Profile 1, 755 Rounded.1,775 Do. 1,725 Do. 1,790 Flattened. 1,965 Do.

A significant property exhibited by corner posts having corrugated steelfoil cores is the ability of the posts to support a load of between zeroand 100 pounds below the maximum supportable load for an indefiniteperiod after initial failure. That is, the posts after failing initiallyunder some maximum compressive force will continue to sustain a loadbetween zero and I00 pounds less than that maximum. This is in contrastto conventional posts having wood veneer cores for which the compressivestrength falls rapidly after the wood first cracks.

Also, posts with corrugated steel foil cores have more con sistantmaximum compressive strengths than do posts with wood veneer cores. Thecompressive strengths for the former vary within a range of about I20pounds while the compressive strengths of the latter posts vary within arange of about 1,000 pounds.

I claim:

l. A packing support comprising first and second paperboard web unitsand a corrugated steel foil core between said units bonded thereto, eachweb unit including at least two plain paperboard webs and a corrugatedpaperboard web therebetween.

2. The support of claim 1 wherein the corrugations in said steel foilcore are substantially flattened.

3. The support of claim 1 wherein said support has an L- shapedconfiguration.

4. The support of claim 3 wherein said steel foil core is secured tosaid web units by means of an adhesive placed along the entire length ofeach of the corrugation peaks in the steel foil core.

5. The support of claim 4 wherein the corrugations in said steel foilcore are substantially flattened. 1

6. The support of claim 4 wherein the steel foil is in a hardened state.

7. The support of claim 4 wherein each of said web units is afive-layered structure comprising alternating plain and corrugated webs,the webs in contact with the steel foil core element being plain webs.

8. The support of claim 7 wherein the steel foil is in a hardened state.

9. The support of claim 8 wherein the steel foil is .006 inch thick.

